Risk of death and cardiovascular events in initially healthy women with new-onset atrial fibrillation

CONTEXT

The risks associated with new-onset atrial fibrillation (AF) among middle-aged women and populations with a low comorbidity burden are poorly defined.

OBJECTIVES

To examine the association between incident AF and mortality in initially healthy women and to evaluate the influence of associated cardiovascular comorbidities on risk.

DESIGN, SETTING, AND PARTICIPANTS

Between 1993 and March 16, 2010, 34,722 women participating in the Women's Health Study underwent prospective follow-up. Participants were 95% white, older than 45 years (median, 53 [interquartile range {IQR}, 49-59] years), and free of AF and cardiovascular disease at baseline. Cox proportional hazards models with time-varying covariates were used to determine the risk of events among women with incident AF. Secondary analyses were performed among women with paroxysmal AF.

MAIN OUTCOME MEASURES

Primary outcomes included all-cause, cardiovascular, and noncardiovascular mortality. Secondary outcomes included stroke, congestive heart failure, and myocardial infarction.

RESULTS

During a median follow-up of 15.4 (IQR, 14.7-15.8) years, 1011 women developed AF. Incidence rates per 1000 person-years among women with and without AF were 10.8 (95% confidence interval [CI], 8.1-13.5) and 3.1 (95% CI, 2.9-3.2) for all-cause mortality, 4.3 (95% CI, 2.6-6.0) and 0.57 (95% CI, 0.5-0.6) for cardiovascular mortality, and 6.5 (95% CI, 4.4-8.6) and 2.5 (95% CI, 2.4-2.6) for noncardiovascular mortality, respectively. In multivariable models, hazard ratios (HRs) of new-onset AF for all-cause, cardiovascular, and noncardiovascular mortality were 2.14 (95% CI, 1.64-2.77), 4.18 (95% CI, 2.69-6.51), and 1.66 (95% CI, 1.19-2.30), respectively. Adjustment for nonfatal cardiovascular events potentially on the causal pathway to death attenuated these risks, but incident AF remained associated with all mortality components (all-cause: HR, 1.70 [95% CI, 1.30-2.22]; cardiovascular: HR, 2.57 [95% CI, 1.63-4.07]; and noncardiovascular: HR, 1.42 [95% CI, 1.02-1.98]). Among women with paroxysmal AF (n = 656), the increase in mortality risk was limited to cardiovascular causes (HR, 2.94; 95% CI, 1.55-5.59).

CONCLUSION

Among a group of healthy women, new-onset AF was independently associated with all-cause, cardiovascular, and noncardiovascular mortality, with some of the risk potentially explained by nonfatal cardiovascular events.

Evaluation of the left atrial substrate in patients with lone atrial fibrillation using delayed-enhanced MRI: implications for disease progression and response to catheter ablation

BACKGROUND

Lone atrial fibrillation (AF) is thought to be a benign type or an early stage of the disease.

OBJECTIVE

This study sought to compare the left atrium (LA) substrate using delayed-enhanced magnetic resonance imaging (DE-MRI) in patients with lone AF versus those with comorbidities.

METHODS

Forty of 333 included patients met criteria for lone AF. All patients underwent DE-MRI to quantify atrial fibrosis as a marker for structural remodeling (SRM) and underwent catheter ablation. Based on the degree of SRM, patients were staged into 4 groups: Utah I (≤5% LA wall enhancement), Utah II (>5% to ≤20%), Utah III (>20% to ≤35%), or Utah IV (>35%).

RESULTS

Distribution in Utah I to IV was comparable in patients with lone AF and non-lone AF. In both groups, a number of patients showed extensive SRM. Mean enhancement (14.08 ± 8.94 vs. 16.94 ± 11.37) was not significantly different between the 2 groups (P = .0721). In the lone AF group, catheter ablation was successful in suppressing AF in all of Utah I, 81.82% of Utah II, 62.5% of Utah III, and none of Utah IV patients. Similar results were achieved in the non-lone AF group. Outcome after ablation was significantly dependent on the SRM of the LA (P < .001).

CONCLUSION

The degree of LA structural remodeling as detected using DE-MRI is independent of AF type and associated comorbidities. Selecting appropriate treatment candidates based on the quality and quantity of atrial fibrosis using DE-MRI would improve procedural outcome and avoid unnecessary intervention.

Lone atrial fibrillation: does it exist?

The historical origin of the term "lone atrial fibrillation" (AF) predates by 60 years our current understanding of the pathophysiology of AF, the multitude of known etiologies for AF, and our ability to image and diagnose heart disease. The term was meant to indicate AF in patients for whom subsequent investigations could not demonstrate heart disease, but for many practitioners has become synonymous with "idiopathic AF." As the list of heart diseases has expanded and diagnostic techniques have improved, the prevalence of lone AF has fallen. The legacy of the intervening years is that definitions of lone AF in the literature are inconsistent so that studies of lone AF are not comparable. Guidelines provide a vague definition of lone AF but do not provide direction about how much or what kind of imaging and other testing are necessary to exclude heart disease. There has been an explosion in the understanding of the pathophysiology of AF in the last 20 years in particular. Nevertheless, there are no apparently unique mechanisms for AF in patients categorized as having lone AF. In addition, the term "lone AF" is not invariably useful in making treatment decisions, and other tools for doing so have been more thoroughly and carefully validated. It is, therefore, recommended that use of the term "lone AF" be avoided.

The hybrid approach for the surgical treatment of lone atrial fibrillation: one-year results employing a monopolar radiofrequency source

BACKGROUND

The hybrid technique combines a mono or bilateral epicardial approach with a percutaneous endocardial ablation in a single-step procedure. We present our early results with this technique employing a monopolar radiofrequency source through a right thoracoscopy in patients with lone atrial fibrillation (LAF).

METHODS

Between June 2009 and December 2010 nineteen consecutive patients (mean 60.8 ± 8.6 years, 84.2% male) underwent right unilateral minimally invasive hybrid procedure for LAF at our Institution. Ten patients (52.6.6%) had long-standing persistent AF while four (21.1%) had persistent and five (26.3%) paroxysmal AF. All patients were followed-up according the Heart Rhythm Society/European Heart Rhythm Association/European Cardiac Arrhythmia Society (HRS/EHRA/ECA) and Society of Thoracic Surgeon (STS) guidelines.

RESULTS

There were neither early nor late deaths. It was possible to complete all the procedures as planned without any conversion to cardiopulmonary bypass. No patient died during the follow up. At one year, 7/19 (36.8%) patients were in sinus rhythm with no episode of AF and off antiarrhythmic drugs (AAD). Time-related prevalence of postoperative AF peaked at 44.4% (41.3-47.4) at two weeks, was 30.4% (27.3-34.9) at three months, fell to 14.2% (11.6-18.1) by 6 months and was 13.3% (11.0-17.4) at 12 months Among patients with long-standing persistent (LSP) AF, 20% (2/10) were in Sinus rythm and off AAD. One-year success rates were 50% (2/4) in persistent and 60% (3/5) in paroxysmal AF. At 12 months estimated prevalence of antyarrhythmic drugs and Warfarin use were 26% (22.4-33.1) and 48% (37.2-53.2), respectively.

CONCLUSIONS

One year results combining the percutaneous endocardial with the right thoracoscopic epicardial technique were, in our experience, not satisfactory, particularly in patients with LSP and persistent AF. Our findings need to be confirmed by larger studies.

Atrial functional tricuspid regurgitation: An underappreciated cause of secondary tricuspid regurgitation

Secondary tricuspid regurgitation (TR) caused by right ventricular enlargement in the setting of left heart disease/pulmonary hypertension has been well described. In contrast, that associated with right atrial enlargement-atrial functional TR (AF-TR)-remains largely underappreciated. AF-TR most often occurs in the setting of lone atrial fibrillation, although it is also seen in its absence (idiopathic AF-TR). Several recent studies have found that the prevalence, hemodynamic significance, and prognosis of AF-TR are not inconsequential, suggesting increased physician awareness of this novel clinical entity is warranted. This article discusses the pathogenesis, echocardiographic findings, and treatment of this underappreciated cause of secondary TR.

IKs Gain- and Loss-of-Function in Early-Onset Lone Atrial Fibrillation

INTRODUCTION

Atrial fibrillation (AF) is the most frequent cardiac arrhythmia. The potassium current IKs is essential for cardiac repolarization. Gain-of-function mutation in KCNQ1, the gene encoding the pore-forming α-subunit of the IKs channel (KV 7.1), was the first ion channel dysfunction to be associated with familial AF. We hypothesized that early-onset lone AF is associated with a high prevalence of mutations in KCNQ1.

METHODS AND RESULTS

We bidirectionally sequenced the entire coding sequence of KCNQ1 in 209 unrelated patients with early-onset lone AF (<40 years) and investigated the identified mutations functionally in a heterologous expression system. We found 4 nonsynonymous KCNQ1 mutations (A46T, R195W, A302V, and R670K) in 4 unrelated patients (38, 31, 39, and 36 years, respectively). None of the mutations were present in the control group (n = 416 alleles). No other mutations were found in genes previously associated with AF. The mutations A46T, R195W, and A302V have previously been associated with long-QT syndrome. In line with previous reports, we found A302V to display a pronounced loss-of-function of the IKs current, while the other mutants exhibited a gain-of-function phenotype.

CONCLUSIONS

Mutations in the IKs channel leading to gain-of-function have previously been described in familial AF, yet this is the first time a loss-of-function mutation in KCNQ1 is associated with early-onset lone AF. These findings suggest that both gain-of-function and loss-of-function of cardiac potassium currents enhance the susceptibility to AF.

Assessment of interleukin-1 gene cluster polymorphisms in lone atrial fibrillation: new insight into the role of inflammation in atrial fibrillation

BACKGROUND

Systemic inflammation is accepted as one of the pathophysiological mechanisms of atrial fibrillation (AF). The role of inflammation has been shown previously. Interleukin (IL) system is the main modulator of the inflammatory responses and genetic polymorphisms of IL-1 cluster genes are associated with increased risk for inflammatory diseases.

OBJECTIVES

To investigate the association between polymorphisms of IL-1 cluster genes and lone AF.

SUBJECTS AND METHODS

DNA samples were collected from 70 proven lone AF patients and 70 healthy subjects. Genomic DNA was typed for the variable number of the tandem repeat (VNTR) IL-1 receptor antagonist (RN) gene polymorphism, IL-1B -511 C > T(rs16944) promoter polymorphism, and +3953 C > T(rs1143634) polymorphism in exon 5 by polymerase chain reaction.

RESULTS

In lone AF group the frequency of IL-1RN2/2 and IL-1RN1/2 genotypes were higher than in the control group (7.2% vs 4.3% and 48.5% vs 22.8%, respectively; χ(2) = 14.1; P = 0.028). The frequency of allele 2 was significantly higher in the lone AF group (32.1% vs 15.7%; χ(2) = 10.7; P = 0.005). Allele and genotype distribution of IL-1B -511 C > T and +3953 C > T polymorphisms were not statistically different between the groups. C-reactive protein (CRP) levels were higher in lone AF patients compared to the control group (median = 1.25, interquartile range [IQR] = 0.85 vs median = 1.08, IQR 0.46 mg/L, respectively; P = 0.02). In multivariate regression analysis, presence of allele 2 of IL-1 VNTR polymorphism and elevated plasma high-sensitive-CRP levels were the independent predictors of lone AF.

CONCLUSION

Presence of allele 2 of VNTR polymorphism of IL-1RN gene may cause increased risk for lone AF probably due to the inadequate limitation of inflammatory reactions.

Left atrial functional remodeling in lone atrial fibrillation: a two-dimensional speckle tracking echocardiographic study

OBJECTIVE

The aim of this study was to assess left atrial (LA) functional remodeling in lone atrial fibrillation (LAF) patients via two-dimensional speckle tracking echocardiography (2DSTE).

METHODS

Forty-five paroxysmal LAF patients and 30 healthy controls underwent 2DSTE in sinus rhythm. Longitudinal LA strain/strain rate (LAS/LASR) of booster, reservoir, and conduit function in apical four- and two-chamber views were measured and averages of the 2 views were used.

RESULTS

The 2 groups had similarity in LA volume. LAS and LASR of the 3 phasic functions were reduced in patients. Comparing the 2 groups, LA booster strain (LASa) and strain rate were -12.31 ± 3.15 versus -15.30 ± 2.52% and -1.64 ± 0.51 versus -2.08 ± 0.48 1/sec, respectively, P < 0.05 for both. Multivariate regression confirmed that LAF was an independent determinant of LAS/LASR reduction. LASa was the most accurate parameter for differentiating LAF patients from controls (area under receiver operating characteristic curve, 0.763; cutoff value, -14.3%; sensitivity, 71.1% and specificity, 70.0%). Finally, LASa decrement was found to be the only significant predictor of early atrial fibrillation (AF) recurrence (odds ratio [OR], 1.39 per unit decrement; 95% CI, 1.02-1.89; P = 0.038).

CONCLUSIONS

Remodeling of LA booster pump, reservoir, and conduit function in LAF patients can be detected by 2DSTE before structural remodeling. Occurrence of LAF is associated with impairment of LA intrinsic myocardial properties. LASa can differentiate LAF patients and lower LASa is associated with early recurrence of AF after ablation.

Catheter Ablation for "Lone" Atrial Fibrillation: Efficacy and Predictors of Recurrence

BACKGROUND

Atrial fibrillation in otherwise healthy young patients has been termed "lone" atrial fibrillation (AF). The best treatment choice is still under discussion. The aim of this study was to report on efficacy and safety of catheter ablation.

METHODS

Among 855 patients referred to our center between 2011 and 2013, 76 (9%) met the diagnostic criteria for lone AF (mean age 45 ± 8 years; mean LA diameter 37 ± 4 mm; paroxysmal AF 82%; persistent AF 18%). The primary endpoint was freedom from any atrial tachycardia after the first ablation; the secondary endpoint was freedom from any atrial tachycardia after the last ablation procedure without antiarrhythmic drugs.

RESULTS

The primary endpoint occurred in 56 patients (74%) after a mean follow-up time of 444 ± 344 days. The secondary endpoint occurred in 73 patients (96%) after a mean of 1.3 ablations/patient during a follow-up time of 459 ± 366 days. The risk of AF recurrence was not influenced by AF duration or by the type of AF (paroxysmal versus persistent). In a multivariate regression analysis smoking (P = 0.001), first degree atrioventricular block (P = 0.001), and early (< 3 months) AF recurrence (P = 0.001) were independently associated with a higher risk of AF recurrence. Major peri-procedural adverse events did not occur.

CONCLUSIONS

Catheter ablation in young healthy patients is highly effective and safe. The outcomes are maintained during long-term follow-up irrespective of preoperative AF duration. Patients with AF recurrence were more likely to smoke, have first degree AV block and early AF recurrence.

Stroke Risk Stratification Schemes in Atrial Fibrillation in the Era of Non- Vitamin K Anticoagulants: Misleading and Obsolete, At Least for the "Low-Risk" Patients?

BACKGROUND

The thromboembolic risk of atrial fibrillation (AF) is significantly mitigated by oral anticoagulation (OAC) therapy, albeit at an increasing bleeding risk. The general principle is that the potential harm conferred by possible bleeding must not exceed the expected protective benefit of OAC. Over the recent years, the CHA2DS2-VASc score has been proven to be superior to other scores in identifying 'low risk' AF patients. However, even this latest score does not incorporate all possible risk factors causing a high thromboembolic risk, while the individual components of the CHA2DS2-VASc score do not seem to carry equal thromboembolic risk. Thus, the quest for more reliable risk stratification schemes and identification of "truly low-risk" patients has been continued.

OBJECTIVE

In this article, data concerning the risk stratification schemes and particularly the CHA2DS2-VASc score of 1 and 0, are critically reviewed and a practical algorithm is proposed for all and more specifically for the "low-risk" patients.

RESULTS

A variety of clinical, echocardiographic, genetic and biochemical or coagulation parameters can also predict adverse thromboembolic events in AF patients. Nevertheless, the addition or adoption of more complex schemes may defeat the purpose of simplicity and practicality, demanding more extensive and costly assessments to decide on a relatively simple question, that of the need for anticoagulation. In the era of non-vitamin K oral anticoagulants (NOACs) proven equivalent or superior to vitamin K antagonists (VKAs), this may not be necessary any more, and a simple recommendation of dispensing OAC therapy almost to every patient afflicted by AF may prove to be a more practical and a ubiquitous approach, as long as safety is ensured by these newer agents.

CONCLUSION

The accumulated evidence appears compelling that at least those with a CHA2DS2- VASc score of ≥1, should receive OAC. With regards to those with a CHA2DS2-VASc score of 0, one may wish to consider additional risk factors (Figure 1) beyond those in scores to decide whether there is a need for thromboembolic protection that outweighs the bleeding risk, preferably with use of NOACs. Finally, an individualized strategy and clinical judgement may be necessary by assessing patient's clinical and financial status, preferences and choices in a shared decision-making or participatory medicine approach.

Cool enough? Lessons learned from cryoballoon-guided catheter ablation for atrial fibrillation in young adults

INTRODUCTION

Cryoballoon (CB)-guided ablation of atrial fibrillation (AF) is established in symptomatic AF patients. This study sought to determine the safety and efficacy of CB pulmonary vein isolation (PVI) in young adults.

METHODS AND RESULTS

A total of 93 consecutive patients aged <45 years referred to our center for AF ablation were included in this observational study. All patients received CB-guided PVI according to a standardized institutional protocol. Follow-up was performed in our outpatient clinic using 72-h Holter monitoring and periodic telephone interview. Recurrence was defined as any AF/atrial tachycardia (AT) episode >30 s following a 3-month blanking period. A propensity matched control group consisting of patients older than 45 years were used for further evaluation. Mean age was 35 ± 7 years, 22% suffered from persistent AF, 85% were male. Mean follow-up was 2.6 ± 2 years. At the end of the observational period, 83% of patients were free of any AF/AT episodes. There was an excellent overall 12-month success rate of 92%. In comparison to a matched group the overall recurrence rate was noticeably lower in the young group (15% vs. 27%). Increasing age was associated with a hazard ratio of 1.16 for recurrence. In a multivariate analysis model, left atrial diameter remained as significant predictor of AF/AT recurrence. The complication rate was low, no permanent phrenic nerve palsy was observed.

CONCLUSION

CB-guided PVI in young adults is safe and effective with favorable long-term results. It may be considered as first-line therapy in this relatively healthy population.

Exercise-Dependent Modulation of Immunological Response Pathways in Endurance Athletes With and Without Atrial Fibrillation

BACKGROUND

Atrial fibrillation (AF) is a common arrhythmia characterized by uncoordinated atrial electrical activity. Lone AF occurs in the absence of traditional risk factors and is frequently observed in male endurance athletes, who face a 2- to 5-fold higher risk of AF compared with healthy, moderately active males. Our understanding of how endurance exercise contributes to the pathophysiology of lone AF remains limited. This study aimed to characterize the circulating protein fluctuations during high-intensity exercise as well as explore potential biomarkers of exercise-associated AF.

METHODS AND RESULTS

A prospective cohort of 12 male endurance cyclists between the ages of 40 and 65 years, 6 of whom had a history of exercise-associated AF, were recruited to participate using a convenience sampling method. The circulating proteome was subsequently analyzed using multiplex immunoassays and aptamer-based proteomics before, during, and after an acute high-intensity endurance exercise bout to assess temporality and identify potential markers of AF. The endurance exercise bout resulted in significant alterations to proteins involved in immune modulation (eg, growth/differentiation factor 15), skeletal muscle metabolism (eg, α-actinin-2), cell death (eg, histones), and inflammation (eg, interleukin-6). Subjects with AF differed from those without, displaying modulation of proteins previously known to have associations with incident AF (eg, C-reactive protein, insulin-like growth factor-1, and angiopoietin-2), and also with proteins having no previous association (eg, tapasin-related protein and α2-Heremans-Schmid glycoprotein).

CONCLUSIONS

These findings provide insights into the proteomic response to acute intense exercise, provide mechanistic insights into the pathophysiology behind AF in athletes, and identify targets for future study and validation.